Moved fake manager creation and initial configuration into the proxy generator (Part I)

This is the first part of PR #372 (we split it up into 2 PRs as mentioned there).

It solves #371 partially, namely that the default behavior is available inside the c'tor call. Therefore it also solves the bug #368 (see the `when_faking_a_class_which_calls_virtual_property_members_in_constructor` test case).
I'm wondering if this name is a bit too general and, whilst the interface currently only has one method, may induce a future violation of http://en.wikipedia.org/wiki/Interface_segregation_principle.

Perhaps something like `IFakeCallProcessor`? (I feel `Object` is redundant in `IWriteablFakeObjectCall` so I've left it out of the suggested name.)